Once a lump of clay has been
prepared or modified to the right consistency/composition, there
are a number of methods by which the potter can shape the clay
into a vessel. Abul-Qasim only mentions throwing on a wheel, which for some
clays is the principal method of formation; however with
relatively non-plastic materials like stonepaste, wheel-throwing
is almost impossible and therefore other techniques are favoured,
especially moulding. What happens to a pot after formation (eg.
paring down, glazing) often obliterates the surface traces of the
technique that was used, so that they can only be seen in X-rays. While
our knowledge of formation methods is frequently derived from
pottery-producing cultures of today, these methods have not
changed all that much over centuries (Technology Part 2: Ethnographic Approaches), and also scientific analysis can give us
an insight into how particular vessels were formed (Technology Part 2: Scientific Approaches). A few actual moulds survive from
Nishapur, all of unglazed, fired clay.

Common methods of constructing
pottery are: pinching and/or drawing; slab-modelling; moulding;
casting; coiling; throwing on a kick-wheel or a turntable.
Several of these techniques may be used in one pot, for example
the component parts of a stonepaste vessel may be thrown
separately on a wheel and then luted together, creating a unique
shape that would be hard to form on a wheel even with a plastic
clay.

consists of opening up
the lump of clay by inserting the thumb or fingers, then
squeezing the clay between the thumb and fingers or the
fingers of both hands. Repeating this action around the
entire lump of clay thins and shapes it in to the desired
form. It is often used for small simple vessels that can
be held in the hand, or for forming the bases of larger
vessels that are built up by other methods.

Drawing

is similar to pinching
but it is used on larger vessels, and uses vertical
movement to open up the lump of clay. The potter
simultaneously squeezes and pinches with an upward
pulling or stretching movement to raise and thin the
walls of the vessel. A tool may be used to scrape the
clay upward.

Slab-modelling

means that the vessel is
constructed from more than one slab of clay. These are
flattened with a rolling pin or patted by hand, then
joined together into the desired shape. It is generally
used to form rectangular shapes but can also be used for
cylinders or very large vessels. A variant of this method
is called "morsel building" in which very small
lumps of clay are flattened and shaped, and joined to
build the walls upward and outward.

Coiling

is perhaps the easiest
method of manufacturing a pot. Coils or ropes of clay are
laid on top and around each other to build up the vessel
circumference and gradually increase its height. There
are different types of coiling: ring building, segmental
coiling or spiral coiling. These are pretty
self-explanatory: in the first type, individual rings are
laid on top of each other; segmental coiling means each
ring is composed of several segments which dont
measure the entire circumference of the pot; spiral
coiling means a long rope of clay is spiralled round the
circumference of the pot. Any or all of these techniques
can be used for the entire pot or for parts of it, where
the other parts are formed by eg. pinching, drawing or
modelling.

As the
pot is built up by successive coils being laid over each
other, the potter squeezes or pinches the coils together
to form a strong bond. The junctions of the coils are
thus obliterated by treatments after the pot shape is
intially formed, and it is thus difficult to see with the
naked eye how the pot was formed, especially if it is
subsequently glazed or covered with a slip. However,
stresses may show during drying if the coils have been
poorly bonded, and it is easy to see with X-ray
photography that the pot has been built up with coils of
clay.

is a variant of moulding
(see below), whereby a thin suspension of fine clay in
water (=a slip) is poured into a mould and allowed to
stand while some of the water is absorbed by the plaster
or earthenware mould; the excess slip is poured off,
leaving a thin layer of fine clay which dries in the
mould.

A section of clay is rolled into a
"pancake" and pressed into or over a prepared mould
made of plaster or fired clay, or even everyday objects such as
baskets: the clay may be applied to the exterior or the interior
of a mould, and the mould may be a single unit or a two-piece
mould (eg. for forming neck and body). Parting agents are used to
prevent the clay from sticking to the mould (eg.ash, fine sand),
however while the clay dries on the mould it shrinks away from
the sides making it easier to remove when fully dry.

The mould itself may be decorated
with incised or relief decoration so that when the clay is firmly
pressed in it acquires the decoration in reverse: this technique
is used in Chinese celadon
wares. A similar technique was used by tile-makers to make relief
quotations from the Quran. Mould-forming can later be
detected on pots through the presence of seams at the juncture or
edges of the mould, or a thin layer of parting agent, or a
contrast in textures between the mould side (smooth) and the
pressed-down or beaten side (rougher).

The type of clay prepared for
throwing is usually softer and wetter than that used in
hand-building techniques, as the air circulation during rotation
on a potters wheel leads to more rapid evaporation and
drying of the body. The clay is also finer-textured to minimise
abrasion of the potters hands. Simple turntables are
common, though the kick-wheel was the type of wheel most often
used. This consisted of two horizontal discs of wood (or some
other hard and not too heavy material), the upper one being the
wheel on which the clay was thrown. This stood at about
table-height or higher and the potter sat in front of it. The
lower disc was the kick-wheel which the potter turned with his
feet as he was throwing the clay, and the two discs were
connected by a vertical shaft.

A lump of clay is placed on a
wheel with its mass carefully centred, or the pot will be
asymmetrical and uneven in thickness. The clay is opened by
inserting fingers into the centre of the mass as it rotates. The
vessel is shaped by "lifting" the clay with one hand
inside and the other outside to draw the walls upward and
outward, thinning them at the same time. This process is aided by
centrifugal force from the spinning of the wheel. The base may be
formed with a modelling tool. The vessel is cut from the wheel
with a knife or wire.

Throwing "from the hump"
is a variant technique in which a very large mass of clay is
centred on the wheel and several vessels are thrown in succession
from the top of the lump. Wheel-thrown vessels can be identified
by "rilling", rhythmic grooves that spiral around the
vessel walls: these may be obliterated by careful smoothing and
may only be visible with X-ray photography. The undersides of the
bases may bear concentric striations caused by removing the
vessel with a wire/knife while the wheel is still rotating.

Different parts of a vessel may be
manufactured in different stages: eg. the lower half may be
moulded, the upper half coiled; the body wheel-thrown and the
neck added by coiling, then smoothed by hand while the pot still
rotates on the wheel. Moulding or hand-modelling is the usual
technique for shaping handles, spouts, supports or decorative
motifs in relief.